BIOL 311 Lecture Notes - Lecture 7: Lactose Intolerance, Lactase, Start Codon

50 views1 pages
Published on 11 Dec 2017
Example of En h a n c e rs Lac to s e intolerance a n d gene
expres s io n
- The enzyme lacta s e is re quired to break la ctos e into glucos e a nd galactose in human
- La cta s e e xpre ssion is significa ntly down-re gula ted (due to e nha nce d transcription) in e a rly
childhood, leading to la ctos e intole ra nce
- Without the expre s s ion of la cta s e , la ctose pas s e s to the colon, whe re it is fe rmente d by
ba cte ria producing the s ymptoms a s socia te d with la ctos e intolerance
- La ctose pers is te nce is the condition tha t a llows a dults to dige s t la ctose. It is inhe rited in an
autos omal dominant fa shion
- How did it e me rge ?
- A cytos ine to thymine transition polymorphis m (S NP) a fe w ba ses after the 5’ of the
initia tion codon of the la ctase gene ha s be e n loca te d a nd implica te d in the obs e rva tion of
la cta s e persiste nce
- Re search ha s s hown that this S NP like ly a ppeare d ~7500 years ago in a re gion betwee n
ce ntra l Balkans a nd centra l Europe. It unde rwent positive selection a mong da iry fa rme rs
- Enha ncer-blocking ins ula tor: re cruits prote ins (tha t either e na ble or preve nt e nha nceos omes
to form) that a llow DNA to get loope d
- Enha ncer must be in the s a me loop a s the promote r for e nha nce osome forma tion
- Ke y P oints
- Ge ne regula tion in e uka ryote s is s imilar to the process in proka ryote s
- However, ma ny more DNA re gulatory s eque nces a nd re gulatory prote ins a re re quired for
the process . S ome DNA regula tory seque nce s ca n be e xtremely fa r upstream from the
promote r
- Re gulatory prote ins bind to DNA regula tory e le ments , but a ls o bind to othe r re gula tory
prote ins. This a llows for the tra ns criptional ma chine ry to be recruited, a nd for chromatin
re modelling to occur
- Enha ncer-blocking ins ula tors pre vent improper enhancer a ctivation, a nd imprope r ge ne
expre s s ion
find more resources at
find more resources at
Unlock document

This preview shows half of the first page of the document.
Unlock all 1 pages and 3 million more documents.

Already have an account? Log in

Get OneClass Notes+

Unlimited access to class notes and textbook notes.

YearlyBest Value
75% OFF
$8 USD/m
$30 USD/m
You will be charged $96 USD upfront and auto renewed at the end of each cycle. You may cancel anytime under Payment Settings. For more information, see our Terms and Privacy.
Payments are encrypted using 256-bit SSL. Powered by Stripe.